Retainer Frame for a Swimming Pool

ABSTRACT

The present invention provides a retainer frame of an outdoor above ground pool, which includes a plurality of posts and a plurality of sets of beams, connected between pairs of adjacent posts to form a polygonal shaped retainer frame. Each beam has two end portions, and each post has one or more receiving ports for receiving the end portions of a set of beams. The retainer frame also includes a plurality of locking members for locking the end portions of the set of beams in the receiving ports of the corresponding post. The beams are capable of swinging around a longitudinal axis of the posts within a range of swinging motion so that the same components (posts, beams and locking members) can be used to form polygonal shaped retainer frames having different numbers of sides.

BACKGROUND OF THE INVENTION

1. Field of the Invention

This invention relates to an outdoor above ground swimming pool structure. In particular, it relates to a retainer frame for such a swimming pool.

2. Description of the Related Art

A conventional type of outdoor above ground swimming pool for family use is an inflatable pool. Such swimming pools have limited size and depth. Another type of outdoor swimming pool uses a multi-layered construction including a retainer frame and a water container made of a plastic material, where the retainer frame has a polygonal shape and the plastic container is mounted on the frame to form a swimming pool of a relatively large size. The retainer frame is typically made of a number of posts and interconnected wood framing with an exterior cover for decorative purposes. The exterior cover is not a structural component and does not contribute to the strength of the retainer frame. The wood framing is often difficult to assemble, and has relatively low structural strength. As a result, the entire pool has relatively low structural strength and limited life. Moreover, because the posts and the framing are fixedly connected together, it is difficult to change the lateral size of the retainer frame without changing the design of the posts and framing.

SUMMARY OF THE INVENTION

Accordingly, the present invention is directed to a retainer frame for a swimming pool that substantially obviates one or more of the problems due to limitations and disadvantages of the related art.

An object of the present invention is to provide a retainer frame for a pool that has a simple structure and high structural strength.

Additional features and advantages of the invention will be set forth in the descriptions that follow and in part will be apparent from the description, or may be learned by practice of the invention. The objectives and other advantages of the invention will be realized and attained by the structure particularly pointed out in the written description and claims thereof as well as the appended drawings.

To achieve these and other advantages and in accordance with the purpose of the present invention, as embodied and broadly described, the present invention provides a retainer frame for a pool, which includes a plurality of posts, a plurality of sets of beams connected between pairs of adjacent posts, each beam having two end portions, wherein each post has one or more receiving ports for receiving the end portions of a set of beams, and a plurality of locking members for locking the end portions of the set of beams in the receiving ports of the corresponding post, wherein the receiving ports have inner dimensions larger than outer dimensions of the end portion of the beams interested therein, and wherein the beams are capable of swinging around a longitudinal axis of the posts within a range of swinging motion.

In another aspect, the present invention provides a method for assembling a retainer frame for a pool, the retainer frame comprising a plurality of posts and a plurality of sets of beams connected between pairs of adjacent posts, each post being formed of one or more tubes with two sets of holes arranged longitudinally on two opposite sides, each beam having an end portion provided with a through hole, wherein the holes on the post are larger than outer dimensions of the beam, the method including the steps of (a) inserting the end portion of a first set of beams into one set of holes on the post such that the through holes of the beam are disposed inside the post; (b) inserting a first locking pin along a longitudinal axis of the post through the through holes of all of the first set of beams; (c) inserting the end portion of a second set of beams into the other set of holes on the post such that the through holes of the beam are disposed inside the post; (d) inserting a second locking pin a longitudinal axis of the post through the through holes of all of the second set of beams; and (e) adjusting an angle formed between a first plane defined by the first set of beams and a second plane defined by the second set of beams by swinging the first and/or second set of beams around a longitudinal axis of the post.

In yet another aspect, the present invention provides a method for assembling a retainer frame for a pool, the retainer frame comprising a plurality of posts, a plurality of sleeves disposed around the posts, and a plurality of sets of beams connected between pairs of adjacent posts, each post having two longitudinal sliding grooves on two opposite sides and a neck portion between the two sliding grooves, each sliding groove having an opening with a width smaller than an inner width of the sliding groove, each sleeve having a longitudinal slit and a set of holes arranged longitudinally on an opposite side of the slit, the sleeve having an interior cross-sectional shape corresponding to an exterior cross-sectional shape of a portion of the post so that the locations of the holes and slit of the sleeve correspond to the locations of the sliding groove and the neck portion of the post, respectively, each beam having an end portion with a neck portion smaller than the opening of the sliding groove, the method including the steps of: (a) sliding the end portions of a first set of beams down along a first sliding groove of a post such that the neck portions of the first set of beams slide along the opening of the first sliding groove, and simultaneously sliding a first sleeve around and along a portion of the post such that the slit of the first sleeve slides along the neck portion of the post, wherein the end portions of the first set of beams have been previously inserted into the holes on the first sleeve; (b) sliding the end portions of a second set of beams down along a second sliding groove of the post such that the neck portions of the second set of beams slide along the opening of the second sliding groove, and simultaneously sliding a second sleeve around and along another portion of the post such that the slit of the second sleeve slides along the neck portion of the post, wherein the end portions of the second set of beams have been previously inserted into the holes on the second sleeve; and (c) adjusting an angle formed between a first plane defined by the first set of beams and a second plane defined by the second set of beams by swinging the first and/or second set of beams around a longitudinal axis of the post.

It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory and are intended to provide further explanation of the invention as claimed.

BRIEF DESCRIPTION OF THE DRAWINGS

FIGS. 1A and 1B are perspective views showing parts of a pool retainer frame according to a first embodiment of the present invention.

FIGS. 2A and 2B are perspective views showing assembled parts of the pool retainer frame of the first embodiment.

FIG. 2C is a cross-sectional view along the A-A section of FIG. 2A.

FIG. 3 is a perspective view showing farther assembled parts of the pool retainer frame of the first embodiment.

FIG. 4 is a perspective view showing a complete pool retainer frame according to the first embodiment.

FIGS. 5A and 5B are perspective views showing parts of a pool retainer frame according to a second embodiment of the present invention.

FIG. 6 is a perspective view showing a complete pool retainer frame according to the second embodiment.

FIGS. 7A, 7B and 7C are perspective views showing parts of a pool retainer frame according to a third embodiment of the present invention.

FIGS. 8 and 9 are perspective views showing assembled parts of the pool retainer frame of the third embodiment.

FIG. 9A is a cross-sectional view along the B-B section of FIG. 9.

FIG. 10 is a perspective view showing a complete pool retainer frame according to the third embodiment.

FIG. 11 is a perspective view showing assembled parts of a pool retainer frame according to a fourth embodiment of the present invention.

FIG. 12 is perspective view showing a complete pool retainer frame according to the fourth embodiment.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Referring to FIGS. 1A to 4, a retainer frame for a swimming pool according to a first embodiment of the present invention includes a plurality of posts 1 and a plurality of sets of beams 2 connected between pairs of adjacent posts. Each post 1 is formed of multiple segments 11 stacked onto each other to form a post of a desired height. Each post segment 11 is formed of two parallel, and preferably round, tubes 111, 112 joined together along their sides. The tubes 111, 112 each have a set (each set having one or more) of holes 113, 114, respectively, arranged along the longitudinal axis on the sides approximately opposite to the side where the tubes are joined together. The holes are preferably located at equal distance from each other. The segment 11 located at the bottom of each post is provided with a base plate 12 at its bottom so that the post can be free standing. The tubes 111′, 112′ of a segment 11 above the bottom segment have end sections 115, 116 with outer dimensions slightly smaller than the inner dimensions of the top end of the tubes, so that the end sections 115, 116 of the tubes 111′, 112′ can be inserted into the top of the tubes 111, 112 of the segment below it to join the two segments together.

The beams 2 are preferably made of metal tubes having a square, round or other suitable cross sections. Each beam 2 is provided with a through hole 21 near each end. Referring to FIGS. 2A-2C, when assembling the retainer frame, a set (each set having one or more) of beams 2 are assembled with a post segment 11 by inserting the end portions of the beams 2 into the set of holes 113 or 114 of the post segment such that the through holes 21 on the beams are located inside the tubes 111 or 112. A locking pin 5 is inserted in the tube and through the through holes 21 of all the beams 2 to prevent the beams from falling out of the post segment 11. Another set of beams 2 (not shown in FIGS. 2A, 2B and 3) are inserted into the other set of holes 114 or 113 of the post segment 11 and similarly locked with a locking pin, so that the two sets of beams 2 extend laterally in approximately opposite directions from the post segment 11 (see FIG. 4). The other end of the beams 2 are inserted into another post segment and locked in a similar manner (see FIGS. 2A and 2B). As shown in FIG. 3, a plurality of post segments 11 with the corresponding beams 2 are stacked vertically to form a desired height. This assembling process is repeated using additional posts and beams to form a pool retainer frame having the shape of an equal-sided (and preferably, but not necessarily, equal-angled) polygon of desired lateral dimensions and height.

Although the posts 1 in FIGS. 1A to 4 are shown as two round tubes connected together, other shapes may be used, such as one round tube with two sets of holes on opposite sides, a square tube, or a tube of any desired cross-sectional shape, so long as there is sufficient space inside the tube to accommodate the ends of two sets of beams inserted therein.

Referring to FIGS. 5A to 6, a retainer frame for a swimming pool according to a second embodiment of the present invention includes a plurality of posts 1 and a plurality of panels 3 connected between pairs of adjacent posts. Each panel 3 is an integrated structure including a plastic cover material and a plurality of metal beams 2 extending horizontally through the panel with their ends exposed. Through holes are formed in the exposed end portions of each beam 2 (see FIG. 5A). The plastic cover material form at least two parallel outer surfaces, but may also have a grid structure in the space between the two outer surfaces. The structures of the rest of the retainer frame are similar to those of the first embodiment described above. The panels 3 and posts 1 are assembled to form a polygonal retainer frame in a manner similar to that of the first embodiment described above. The panels 3 provide a more pleasing appearance to the retainer frame, and also function to provide additional strength for the retainer frame as well as better support for the plastic pool retained inside the frame.

Referring to FIGS. 7A to 10, a retainer frame for a swimming pool according to a third embodiment of the present invention includes a plurality of posts 1′ and a plurality of sets of beams 2 connected between pairs of adjacent posts. As shown in FIG. 7A, each post 1′ has an elongated shape with two parallel sliding grooves 13 located on two sides thereof. A neck portion 14 is formed between the two vertical sliding grooves 13, such that the cross-sectional shape of the post generally resembles two C-shaped portions joined together. The width of the opening of the sliding groove 13 is smaller than a width of the interior of the grooves.

As shown in FIG. 7B, 7C and 8, a set (each set having one or more) of metal beams 2 are arranged in parallel and connected at their ends to two sleeves 4. Each sleeve 4 is provided with a plurality of holes 41 arranged along its longitudinal axis, preferably at equal distance from each other, and a longitudinal slit 42 on the opposite side facing the holes 41 (see FIG. 7B). The interior cross-sectional shape of the sleeve 4 is similar to the exterior cross-sectional shape of the C-shaped portions of the post 1′, where the location of the holes 41 corresponds to the location of the groove 13 and the location of the slit 42 corresponds to the location of the neck portion 14. As shown in FIG. 7C, a neck portion 22 is formed at each end of the beam 2, where the width of the neck portion is slightly smaller than the width of the opening of the sliding groove 13 of the post 1′.

When assembling (see FIGS. 8, 9 and 9A), the end portions of the beams 2 are inserted into the holes 41 of a sleeve 4. To prevent the end portions of the beams 2 from falling out of the sleeve 4, a through-hole 21 may be provided in each end portion of the beams 2 (see FIG. 7), and a locking pin 5 may be inserted into the sleeve 4 and through the through-holes of all the beams 2 (see FIG. 8). Then, the sleeve 4 with the beams 2 are mounted onto posts 1′ by inserting the end portions of the beams 2 into one of the sliding grooves 13 of the posts 1′ and sliding them down, and at the same time sliding the sleeve 4 down around the outside of the C-shaped portions of the posts 1′ (see FIGS. 9 and 9A). The other end of the beams 2 are assembled with another sleeve 4 and mounted onto another post in a similar manner (see FIGS. 8 and 9). In addition, another set of beams 2 (not shown in FIG. 9) with a sleeve 4 are mounted onto the other side of the post 1′ using the other sliding groove 13 in a similar manner, so that the two sets of beams 2 extend laterally in approximately opposite directions from the post 1′. Also, as shown in FIG. 9, the sleeves 4 may be shorter than the posts 1′, and a plurality of sleeves 4 with beams 2 may be stacked on top of each other and mounted on the posts 1′. This assembling process is repeated using additional posts, sleeves and beams to form a pool retainer frame having the shape of an equal-sided (and preferably, but not necessarily, equal-angled) polygon of desired lateral dimensions. In addition, although not shown, the posts 1′ may be made of multiple segments stacked onto each other, similar to the posts in the first and second embodiments, to form a pool retainer frame of a desired height.

As shown in FIG. 9A, when mounted, the neck portion 22 of each beam 2 is located at the opening of the sliding groove 13, and the end portion of the beam 2 is retained inside the groove 13. In addition, the vertical slit 42 of the sleeve 4 is located at the neck portion 14 of the post 1′. As a result, the beams 2 and the sleeves 4 are securely mounted to the posts 1′. If should be pointed out that the pin 5 is not necessary for retaining the beams 2 inside the sliding grooves 13, but merely prevents the beams from falling out of the holes 41 of the sleeve 4 during assembling. The cross-sectional shape of the posts 1′, sleeves 4, and end portions of the beams 2 may vary from those shown in the drawings, so long as the end portions of the beams 2 are securely retained inside the groove and the sleeve is securely retained around the post.

Referring to FIGS. 11 and 12, the retainer frame for a swimming pool according to a fourth embodiment of the present invention includes a plurality of posts 1 and a plurality of panels 3 connected between pairs of adjacent posts. Each panel 3 is an integrated structure including a plastic material and a plurality of metal beams 2 extending horizontally through the panel with their ends exposed. The plastic cover material form at least two parallel outer surfaces, but may also have a grid structure in the space between the two outer surfaces. The structure of the end portions of the beams 2 and the structures of the rest of the retainer frame (including the post I′ and the sleeve 4) are similar to that of the third embodiment described above. The panels 3, sleeves 4 and posts 1′ are assembled to form a polygonal retainer frame in a similar manner as in the third embodiment. Each panel and the corresponding two sleeves may be pre-installed prior to shipping to customers. The panels 3 provide a more pleasing appearance to the retainer frame, and also function to provide additional strength for the retaining frame as well as better support for the plastic pool retained inside the frame.

In the above-described embodiments, the posts 1 or 1′, the beams 2, and the sleeves 4 are preferably made of metal, such as steel, but may also be formed of any other suitable material. The plastic cover material of the panels 3 is preferably made of extruded PVC, but may also be made of any other suitable material.

In all of the above-described embodiments, the pool retainer frame includes a plurality of posts 1 or 1′ and a plurality of beams 2 connected to the posts. The lateral dimensions of the entire pool retainer frame are determined by the number of posts in the frame, i.e., the number of sides in the polygon. To allow retainer frames of different sizes to be built using the same posts and beams (but different numbers thereof), the connection of the beams 2 to the posts 1 or 1′ is designed to allow the beams 2 to have a degree of freedom to swing in the horizontal plane around a longitudinal axis of the post. Thus, when assembled, the angle formed between a plane defined by a set of beams 2 connected to one side of a post 1 or 1′ and a plane defined by a set of beams connected to the other side of the post (or two panels 3 connected on two sides of a post) is adjustable in a range to provide an appropriate angle as required by the desired number of sides in the retainer frame. For example, if the retainer frame is a 12-sided regular polygon (a polygon having equal sides and equal angles), the angle formed by two adjacent sides of the polygon is 150 degrees; if the retainer framing is a 24-sided regular polygon, the angle is 165 degrees, etc. Thus, to enable the same posts and beams to form regular polygons having a number between 12 and 24 sides, the beam to post connection structure should be designed to allow the angles between two sets of beams connected to a post to range from 150 to 165 degrees. Of course, the range of angles is not limited to the above examples. The ability of the beams to swing also allows a certain degree of flexibility and tolerance in the shape of the assembled pool retainer frame.

In the first and second embodiments, the range of the swinging motion of the beams is accomplished by making the holes 113, 114 on the tubes 111, 112 slightly larger than the outer dimensions of the beams 2. As shown in FIG. 2C, when the end portion of a beam 2 is inserted into a hole 114 of the tube 112 and locked by a locking pin 5, the beam 2 can swing within a range about a longitudinal axis of the tube 112. Also as shown in FIG. 2C, the two sets of holes 113 and 114 are not oriented at exactly 180 degrees away from each other; rather, they may be oriented at an offset angle, such as 160 degrees, from each other. In the third and fourth embodiments, the range of swinging motion of the beams is accomplished by making the end portion and the neck portion 22 of the beam 2, respectively, slightly smaller than the interior size and the opening width of the groove 13, respectively (see FIG. 9A). The holes 41 on the sleeve 4 are also slightly larger than the size of the beam 2, so the beams can swing within a range about a longitudinal axis of the post 1′. Also, as shown in FIG. 9A, the openings of the two sliding grooves 13 are not oriented at exactly 180 degrees away from each other; rather, they may be oriented at an offset angle, such as 160 degrees, from each other.

More generally, a retainer frame according to embodiments of the present invention includes a plurality of posts and a plurality of sets of beams connected between pairs of adjacent posts. Each beam has two end portions, and each post has one or more receiving ports (the holes 113, 114 in the first and second embodiments, or the grooves 13 in the third and fourth embodiments) for receiving the end portions of a set of beams. The retainer frame also includes a plurality of locking members (the locking pin 5 in the first and second embodiments, or the sleeves 4 in the third and fourth embodiments) for locking the end portions the set of beams in the receiving ports of the corresponding post. The receiving ports have inner dimensions larger than outer dimensions of the end portion of the beams interested therein, such that the beams are capable of swinging around a longitudinal axis of the posts within a range of swinging motion.

In summary, the modular structure of the pool retainer frame according to embodiments of the present invention provides excellent scalability for the retainer frame in both the vertical and lateral directions.

It will be apparent to those skilled in the art that many other various modification and variations can be made in the pool retainer frame of the present invention without departing from the spirit or scope of the invention. Thus, it is intended that the present invention cover modifications and variations that come within the scope of the appended claims and their equivalents. 

1. A retainer frame for a pool, comprising: a plurality of posts; a plurality of sets of beams connected between pairs of adjacent posts, each beam having two end portions; wherein each post has one or more receiving ports for receiving the end portions of a set of beams; and a plurality of locking members for locking the end portions of the set of beams in the receiving ports of the corresponding post; wherein the receiving ports have inner dimensions larger than outer dimensions of the end portion of the beams interested therein, and wherein the beams are capable of swinging around a longitudinal axis of the posts within a range of swinging motion.
 2. The retainer frame of claim 1, wherein the each post is formed of one or more tubes, wherein the receiving ports are formed of two sets of holes arranged longitudinally on two opposite sides of the tubes, wherein the end portion of each beam has a through hole, wherein the end portions of the beams including the through holes are inserted through the holes of the post, wherein the locking members are a plurality of locking pins each inserted into a post and through the through holes of the end portions of the beams, and wherein the holes of the posts are larger than an outer dimension of the beam inserted therein.
 3. The retainer frame of claim 2, wherein each post is formed of two parallel round tubes connected together along a side, each tube having a set of holes.
 4. The retainer frame of claim 1, wherein the receiving ports of each post are two longitudinal sliding grooves on two opposite sides of the post, each sliding groove having an opening with a width smaller than an inner width of the sliding groove, the post further having a neck portion between the two sliding grooves, wherein the locking members are a plurality of sleeves each disposed around a portion of a post, each sleeve having a longitudinal slit and a set of holes arranged longitudinally on an opposite side of the slit, the sleeve having an interior cross-sectional shape corresponding to an exterior cross-sectional shape of a portion of the post such that the locations of the holes and slit of the sleeve correspond to the locations of the sliding groove and the neck portion of the post, respectively, wherein the end portion of each beam is inserted though a hole of a sleeve and retained in one of the sliding grooves of a post, the end portion of the beam having a neck portion located at the opening of the sliding groove, and wherein the opening of the sliding groove is larger than the neck portion of the beam and the holes on the sleeves are larger than an outer dimension of the beam inserted therein.
 5. The retainer frame of claim 4, wherein the end portion of each beam retained inside the groove has a through hole, and wherein the retainer frame further comprises a plurality of locking pins each inserted into the through holes of the end portions of the beams.
 6. The retainer frame of claim 1, wherein each post is formed of one or more post segments connected at their ends to form a desired height.
 7. The retainer frame of claim 6, wherein at least some of the post segments have a first end section with outer dimensions smaller than inner dimensions of a second end section thereof, thereby allowing the first end section of a post segment to be inserted into a second end section of another post segment.
 8. The retainer frame of claim 1, further comprising a cover material covering the sets of beams with the end portions of the beams exposed, each set of beams and corresponding cover material forming a panel having an integrated structure, each panel being connected between a pair of adjacent posts.
 9. A method for assembling a retainer frame for a pool, the retainer frame comprising a plurality of posts and a plurality of sets of beams connected between pairs of adjacent posts, each post being formed of one or more tubes with two sets of holes arranged longitudinally on two opposite sides, each beam having an end portion provided with a through hole, wherein the holes on the post are larger than outer dimensions of the beam, the method comprising: (a) inserting the end portion of a first set of beams into one set of holes on the post such that the through holes of the beam are disposed inside the post; (b) inserting a first locking pin along a longitudinal axis of the post through the through holes of all of the first set of beams; (c) inserting the end portion of a second set of beams into the other set of holes on the post such that the through holes of the beam are disposed inside the post; (d) inserting a second locking pin a longitudinal axis of the post through the through holes of all of the second set of beams; and (e) adjusting an angle formed between a first plane defined by the first set of beams and a second plane defined by the second set of beams by swinging the first and/or second set of beams around a longitudinal axis of the post.
 10. The method of claim 9, further comprising: repeating the steps (a)-(e) using additional posts and beams to form a polygonal shaped retainer frame.
 11. The method of claim 9, wherein each post comprises a plurality of post segments, the method further comprising: connecting a plurality of post segments at their ends to form posts.
 12. The method of claim 9, wherein each set of beams is a part of an integrated panel made of the set of beams and a cover material.
 13. A method for assembling a retainer frame for a pool, the retainer frame comprising a plurality of posts, a plurality of sleeves disposed around the posts, and a plurality of sets of beams connected between pairs of adjacent posts, each post having two longitudinal sliding grooves on two opposite sides and a neck portion between the two sliding grooves, each sliding groove having an opening with a width smaller than an inner width of the sliding groove, each sleeve having a longitudinal slit and a set of holes arranged longitudinally on an opposite side of the slit, the sleeve having an interior cross-sectional shape corresponding to an exterior cross-sectional shape of a portion of the post so that the locations of the holes and slit of the sleeve correspond to the locations of the sliding groove and the neck portion of the post, respectively, each beam having an end portion with a neck portion smaller than the opening of the sliding groove, the method comprising: (a) sliding the end portions of a first set of beams down along a first sliding groove of a post such that the neck portions of the first set of beams slide along the opening of the first sliding groove, and simultaneously sliding a first sleeve around and along a portion of the post such that the slit of the first sleeve slides along the neck portion of the post, wherein the end portions of the first set of beams have been previously inserted into the holes on the first sleeve; (b) sliding the end portions of a second set of beams down along a second sliding groove of the post such that the neck portions of the second set of beams slide along the opening of the second sliding groove, and simultaneously sliding a second sleeve around and along another portion of the post such that the slit of the second sleeve slides along the neck portion of the post, wherein the end portions of the second set of beams have been previously inserted into the holes on the second sleeve; and (c) adjusting an angle formed between a first plane defined by the first set of beams and a second plane defined by the second set of beams by swinging the first and/or second set of beams around a longitudinal axis of the post.
 14. The method of claim 13, further comprising: repeating the steps (a)-(c) using additional posts, sleeves and beams to form a polygonal shaped retainer frame.
 15. The method of claim 13, wherein each post comprises a plurality of post segments, the method further comprising: connecting a plurality of post segments at their ends to form posts.
 16. The method of claim 13, further comprising: (d) before step (a), inserting the end portion of the first set of beams into the holes on the first sleeve; and (e) before step (b), inserting the end portion of the second set of beams into the holes on the second sleeve.
 17. The method of claim 16, wherein the end portion of each beam has a through hole, the method further comprising: (f) after step (d) and before step (a), inserting a locking pin inside the sleeve through the through holes of all of the first set of beams; and (g) after step (e) and before step (b), inserting a locking pin inside the sleeve through the through holes of all of the second set of beams.
 18. The method of claim 13, wherein each set of beams is a part of an integrated panel made of the beams and a cover material. 